Mechanism of NO removal by NH3 + CO coupling over Fe-Ce/AC catalyst at low temperature

Abstract

In order to explore the activity and mechanism of low-temperature NH₃ + CO coupling removal of NO by catalysts prepared by loading transition metal element Fe and rare earth element Ce into activated carbon, Fe/AC, Ce/AC and Fe-Ce/AC catalysts were prepared in this paper. Based on the test of NO conversion rate and characterization of physicochemical properties of catalysts, the mechanism of low-temperature NH₃ + CO coupling removal of NO by catalysts was proposed. The results show that the Fe-Ce/AC catalyst has higher NO conversion than the single metal supported catalyst. Although the surface of Fe-Ce/AC catalyst is rough, the pores are fully developed, and the metal oxides are better loaded and uniformly dispersed. The N₂ isothermal adsorption-desorption curve showed typical I-type and IV-type isotherms, with H₄-type hysteresis loop. Ce doping makes Fe uniformly loaded, the diffraction peaks of metal oxides weakened. Fe-Ce/AC has more oxygen-containing functional groups and oxygen vacancies than single metal supported catalysts. The Fe-Ce/AC catalyst is dominated by physical adsorption and L-H mechanism before 150 °C. Some Ce active components are dominated by E-R mechanism at 150∼200 °C. After 200 °C, the E-R mechanism is dominant.